Interesting, the profile suggests that the only real visible difference is that females are thicker. I've read that males are universally black though while females have gray bellies. I've always called mine a female because she is a chubby fish and has a gray belly.

Interesting, the profile suggests that the only real visible difference is that females are thicker. I've read that males are universally black though while females have gray bellies. I've always called mine a female because she is a chubby fish and has a gray belly.

Thanks for mentioning this. I just checked back through my normal sources and one does mention this, and another mentions females having a less-pointed dorsal, though this is unreliable. Others don't.

As you have experience, do you think either trait is reliable? I could always say "some authors say..." to make it less absolute, that's acceptable.

The aquarist is one who must learn the ways of the biologist, the chemist, and the veterinarian.[unknown source]

Something we all need to remember: The fish you've acquired was quite happy not being owned by you, minding its own business. If you’re going to take it under your wing then you’re responsible for it. Every aspect of its life is under your control, from water quality and temperature to swimming space. [Nathan Hill in PFK]

I will definitely try and get some pictures posted tonight of the red tail and the pleco. We are going to get some better/more decorations for the tank and some live plants this weekend. I also want to change out the black/blue gravel for a more natural sand color. I don't know why I went with the black/blue in the first place.

The aquarist is one who must learn the ways of the biologist, the chemist, and the veterinarian.[unknown source]

Something we all need to remember: The fish you've acquired was quite happy not being owned by you, minding its own business. If you’re going to take it under your wing then you’re responsible for it. Every aspect of its life is under your control, from water quality and temperature to swimming space. [Nathan Hill in PFK]

I think we are going to see about taking the red tail back to the lfs. I sat at the aquarium watching them before I did the partial water change and he was really aggressive today. I think he may be getting more comfortable though as now that the ammonia is down it seems like he has gotten a little darker. We have our dslr camera at our house so I was only able to take pictures with my phone. I don't think they turned out that great but I will post them in another post from my phone.

Well, the gray can be stress but at a young age they aren't perfectly coal black either. Also the lighting can have an effect on their color. My QT tank's light always washed my RTBS's colors out. I will say the ring round his eye is a new one on me. Never seen that before. Is that an artifact of taking the picture of does he really have the yellow ring?

Water changes can alter behavior. Some of my fish love them, some hate them. My rummynose tetras play in the water as I add it. They will swim to where it's pouring in and keep pace. My RTBS on the other hand loathes them. She dives into another cave in the very back of the tank and will not come out. In fact a memorable "freak out" on her part occurred during a water change. Also after a water change my cory's will be far more active than before it. A water change can stress fish out or promote behaviors you don't normally see.

Taking him back is probably for the best. Personally I'd just get a larger tank but then I'm kind of a nut for them.

I am pretty sure the yellow ring is an artifact from the camera. I don't have our slr to take a good picture of them with. We are moving the last of our stuff this weekend and since we are moving the tank I may take the opportunity to get a bigger tank. The AC filter I have is for a 50 gallon tank so the only thing I should have to get extra would be a lid. I would like to keep the red tail because if he/she gets like the one in your avatar I think it is an awesome looking fish. According to what you and Byron posted I think our red tail might be a female. She is plumper and has a little more of a rounded dorsal fin. I pulled the bleeding heart tetra out and put her in the 5 gallon tank we have as an extra and everyone in the tank seems to be getting a long great. They are almost all staying close to each other too. I didn't think the bleeding hearts were an aggressive fish but the one we had was. She would chase anyone that came within 6" of her. The red tail definitely has it's own place under the one decoration. None of the other fish ever go under there except for the red tail now.

More than likely that's "his" cave and he's run off some of the other fish when they get too close. I'd be careful about judging sex just yet as your RTBS is still growing a great deal. I'd wait until they're about 4+ inches before trying to sex them. From what I've read if you get a solid black fish, like my avatar, it's male. If they have a gray belly it's a female (like mine at home.)

If you do decide to get a larger tank a 40 Breeder or a 50 gallon (not the long skinny 55) would be ideal and give your RTBS about 80% more bottom area to prowl.